Voltage regulator



May 25,1943. A. L. HOPPER 2,320,237

VOLTAGE REGULATOR Filed Oct. 12, 1940 v INVENTOR- By A.L.HOPPER ZATTORNEY Patented May 25, 1943 UNITED STATES PATENT OFFICE VOLTAGEREGULATOR Andrew L. Hopper, River Edge, N. 1., assignor to BellTelephone Laboratories, Incorporated, New York, N. Y., a corporation ofNew York Application October 12, 1940, Serial N0. 360,911

9 Claims. (Cl. 171-312) Thisinvention relates to voltage regulators andparticularly to voltage regulators employing gas-filled space dischargedevices.

One object of the invention is to provide a voltage regulator between asupply circuit and a load circuit that shall employ gas-filled spacedischarge devices in an improved manner to effect first an approximateadjustment and then an accurate adjustment of the voltage supplied tothe load circuit.

Another object of the invention is to provide a voltage regulatoremploying gas-filled tubes and resistance elements between a supplycircuit and a load circuit that shall ignite the gasillled tubes inparallel circuits connected to the supply circuit and that shallmaintain constantvoltage on the load circuit by connecting the tubes intandem between the supply circult and the load circuit.

A further object of the invention is to provide a voltage regulator ofthe above-indicated type that shall connect each tube in series with aresistance element and the tubes with associated resistance elements inparallel to the supply circult to ignite the tubes and that shallconnect one tube in series with a resistance element across the supplycircuit, the second tube in series with a resistance element across thefirst tube and the load circuit across the second tube to maintain theload voltage substantially constant.

Vacuum tubes of many types are used in electric circuits and in manycases it is essential to maintain the voltage of the plate supply forthe tubes substantially constant. It is desirable in many instances toprovide a voltage regulator for the plate supply of the tubes that shallbe free of any moving parts and that shall have a low maintenance cost.

According to the present invention a voltage regulator is provided forthe plate supply of tubes in a measuring circuit of a telegraph linethat shall be free from moving parts and that shall have a low firstcost and a low maintenance cost.

The regulator consists essentially of two gasfilled tubes, a number ofresistance elements and I supply circuit. In the second position of theswitch the operating circuit of the three-element cold cathode tube isconnected through two parallelly arranged resistance elements across thesupply circuit. The two-element tube is connected in series with aresistance element across the three-element tube and the load circult isconnected across the two-element tube. In the first position of theswitch the two cold cathode tubes are connected across the supplycircuit in parallel and ignited and in the'second position or the switchthe two cold cathode tubes are operated in tandem for supplying asubstantially constant voltage to a load circuit.

A gas-filled tube, as for example, a cold cathode tube may be employedas a voltage regulator if connected across a source in series with aresistance element. The current flow through the cold cathode tube willvary in accordance with voltage variations of the source but thepotential across the tube will not vary with the voltage variations ofthis source. The voltage variations of the source are absorbed by theresistance in series with the cold cathode tube. In experiments whichhave been performed, it is found. that ii the source has a 10 per centvariation, the voltage drop across the first tube will have a voltagevariation of the order of 1 per cent and the voltage variations acrossthe second tube will be of the order or .1 per cent. Resistance elements01' dli'ierent value are employed in the ignition and operation of thecold cathode tubes in order to insure that the current flow througheither of the cold cathode tubes is limited to a sale value.

In the accompanying drawing, Fig. 1 is a diagrammatic view of a voltageregulator constructed in accordance with the invention;

Fig. 2 is a diagrammatic view of the ignition circuits for the tubes inthe voltage regulator shown in Fig. 1;

Fig. 3 is a diagrammatic view of the operating circuits for the voltageregulator shown in Fig. l; and,

Fig. 4 is a diagrammatic view of a. modification of the regulator shownin Fig. 1.

trodes i2 and i3.

Referring to Fig. 1 of the drawing, a voltage regulator I is shownconnected between a direct current source comprising a battery 2 anda'load shown as a resistance 3. The regulator comprises a three-elementcold cathode tube 3, a two-element cold cathode tube 5, four resistanceelements 5, I, 8 and -9 and a switch HI. The

tube 4 is provided with three electrodes H, II

'and I3 and the tube 5' is provided with twoelectrodes l4 and IS. Theswitch iii is provided with three switch members l5, l1 and i8-and fourcontact members 13, 20, 2! and 22. The

two tubes 4 and 5 are illustrated as gas-filled A 8.600 ohms, theresistance 9 was made 2,500 ohms.

the resistance 5 was made .1 'megohm and the load was made 20,000 ohms.

Assuming the switch ID to be in the startin position, a circuit iscompleted from the battery 2 for breaking down the tube 4 across theelec- This circuit may be traced from ground through the battery 2,resistance element 6, contact member I9, switch member 18 and electrodes12 and-i3 to ground. tube breaks down when 70 volts are impressed acrossit. At the same time thetube 5 breaks down by means of a circuit whichmay be traced from ground through the battery 2, resistance elements 8and 9 and the electrodes l5 and ii to ground. The tube 5 breaks downwhen approximately 79 volts are impressed across it. A die grammaticview of the circuit completed by the switch it for igniting two tubes 4and 5 is shown in Fig. 2 of the drawing. In Fig. 2 it will be noted thatthe two tubes 4 and 5 are connected in parallel to the battery 2. Uponbreakdown or ignition of the tube 4, a sustaining circuit is completedthrough the electrodes H and 13. This circuit may be traced from groundthrough the batteryl, resistance element I and the electrodes H and I3to ground.

In the operating position of the switch it which is shown in Fig. 1 ofthe drawing, the two tubes 4 and 5 are connected in tandem between theresistance element 3 is connected across the tube 5. The voltage acrossthe electrodes of the tube 4 is maintained approximately constant andthe voltage across the electrodes of the tube 5 is maintainedsubstantially constant. In the operating circuit shown in Fi 3 0! thedrawing,

the voltage variations of the source with respect to the tube 4 areabsorbed by the resistance elements '1 and 8 and the voltage variationssupplied to the tube 5 are absorbed by the resistance element 3.

Referring to Fig. 4 or the drawing, a regulator circuit similar totheregulator circuit shown in Fig. 1 is provided wherein the operatingswitch is eliminated. The regulator shown in Fig. 4 comprises two coldcathode tubes 30 and 3!, four resistance elements 32, 33, 34 and 35 andtwo condensers 36 and 31. -The two tubes 30 and 3| are energized from abattery 38 for supplying constant voltage to a load 33. The tube 30comprises two electrodes 40 and 4| and a strap 42 included in the baseoi. the tube. The strap 42 prevents excess current in tube 3! in casetube 39 isremoved from its socket. The tube 30 may be an RCA874. Thetube 3| isprovided with two electrodes 43 and 44.

The two tubes 33 and 3| are ignited by means of two parallel circuitsconnected to battery 38. The ignition circuit for the tube 38 may betraced from ground through the battery 38, condenser 37, resistance 33and the electrodes 4! and 40 to ground. The ignition circuit for thetube 3! may be traced from ground through the battery 38, condenser 36,resistance 35 and the electrodes 44 and 43 to ground. Upon ignition thetubes 30 and 3| are operated in tandem between the source and the load.The operating circuit for the tube 33 may be traced from ground throughthe battery- 33, resistance element 32 and electrodes 41 and W toground. The operating circuit for the tube 31 may be traced from theconductor between the resistance 32 and electrode 4! through theresistance element 34 and the electrodes 44 and 43 to ground. The loadis connected the source comprising the battery 2 and the load comprisingthe resistance 3. The operating an cuit for the tube}! may be tracedfrom ground through the battery 2, resistance elements i and 3 inparallel, electrode H and the electrodes 43 and I3 in parallel toground. The operating volt age across the tube I is in the neighborhoodof volts. The operating circuit for the tube li may be traced from theconductor between the resistance element 1 and the electrode 11' of theyThe tube 5 is shown connected in circuit with the resistance element 9across the tube 4 and across the tube 3!.

The tube 30 breaks down when 125 volts are impressed across it and isoperated when volts are impressed on it. The tube 3i breaks down when70, volts are impressed across it and is operated when 60 volts areimpressed on it. In the regulator shown in Fig. 4 of the drawing it willbe noted that the two tubes 33 and SH are ignited in parallel circuitrelation and are operated in tandem relation.

Modifications in the circuits and in the arrangement and location ofparts may be made within the spirit and scope of the invention and suchmodifications are intended to be covered by the appended claims.

What is claimed is:

1. In a voltage regulator connected between a load circuit and a currentsupply circuit, two cold cathode tubes, a plurality of resistanceelements, means ior igniting a first one of said tubes from said supplycircuit through a first one of said resistance elements and the secondof said tubes through a second and a third ones of said resistanceelements in series and means for estabiishing an operating circuit forsaid first one oi said tubes from said supply circuit through a fourthone and said second one of said resistance elements in parallel, forestablishing an operating circuit for the second tube from across saidfirst tube through said third resistance element and for energizing theload circuit by the potential drop across said second tube.

2. In a voltage regulator connected between a load circuit and a directcurrent supply circuit, two cold cathode tubes, a plurality ofreresistance elements, means for igniting each oi said tubes from saidsupply circuit through selected ones of said resistance elements and forholding the tubes ignited and means including diflerent selected ones ofsaid resistance elements for establishing an operating circuit for a.first one of said tubes from said supply circuit, for establishing anoperating circuit for the second tube from across said first tube,whereby the voltage across said first tube is that supplied to theoperating circuit of said second tube, and for energizing the loadcircuit by the potential drop across the second tube, said second meansrendering ineffective the ignition paths for said tubes when saidoperating circuits are established.

, 3. In a voltage regulator connected between 1 a supply circuit and aload circuit, two gas-filled tubes, a plurality of resistance elements,means for connecting each of said tubes in series with a resistanceelement and for connecting the two tubes with the associated resistanceelements in parallel circuits across said supply circuit to efi'ectignition of the tubes, and means connec ing the supply circuit acrossone tube and for connecting the last--mentioned tube in series with aresistance element across the other tube.

4. In a voltage regulator connected between.

a load circuit and a direct current supply circuit, a first cold cathodetube. a second two element cold cathode'tube, a plurality of resistanceelements, and means comprising a switch in one position for ignitingeach of said tubes from said supply circuit and in a second position forigniting the first tube in series with one of said resistance .elementsfor said supply circuit, for operating the second tube in series withanother of said resistance by the potential drop across said first tubeand for energizing the load circuit by the potential drop across saidsecond tube.

5. In a voltage regulator connected between a load circuit and a directcurrent supply circuit, a first three-element cold cathode tube, asecond two-element cold cathode tube, a plurality of resistanceelements, means for igniting the three-element tube in series with oneof said resistance elements from said supply circuit and for completinga holding circuit for the tube through a second one of said resistanceelements, means for igniting said two-element tube in circuit with twoof said resistance elements from said supply circuit, and means forestablishing an operating circuit for the. first tube said first tubethrough one of said resistance elements and for energizing the loadcircuit by the potential drop across said second tube.

in one position for disconnecting the load from said second tube and forigniting each of said tubes from said source and in a second positionfor connecting the first tube in series with refor connecting theigniting circuit of the first tube in series with one of said resistanceelementsto said source to ignite the tube, for establishing a holdingcircuit from the supply circuit through a second one of said resistanceelements and for igniting the second tube in series with two of saidresistance elements from said supply circuit and in a second switchposition for connecting the operating circuit of the first tube throughtwo of said resistance elements in parallel to the source, iorconnecting the second tube in series with one of said resistanceelements across said first tube and for connecting the load circuitacross said second tube.

8. In a voltage regulator connected between a direct current supplycircuit and a load circuit, two gas-filled tubes, a plurality ofresistance elements, two capacity elements, means for connecting each ofsaid tubes in series with one of said resistance elements and one ofsaid capacity elements and for connecting the two tubes with theassociated resistance and capacity elements across said supply circuitto effect ignition of the tubes and means for connecting a first one ofsaid tubes in series with a resistance element .across the supplycircuit, for connecting the second tube in series with a resistanceelement across the first tube and for connecting the load circuit acrossthe second tube.

9. In a voltage regulator connected between a load circuit and a directcurrent source of supply, two gas-filled tubes, two resistance means,means for connecting said source, said load. and said two resistancemeans in series relation, means for connecting one of said tubes inshunt between one terminal of said source and a point between said tworesistance means and the other of said tubes in shunt between oneterminal of said source and a point between said resistance means andsaid load, whereby the potential difference across said one tube isgreater than that across said other tube, and means for temporarilyimpressing across each of said tubes a potential diflerence derived fromsaid source greater than said first-mentioned potentinl diflerencethereacross to start said tubes into operation, said last-mentionedmeans e!- 6. In a voltage regulator circuit two cold cathode tubeshaving diflerent ignition and operating voltages, at variable source ofdirect current, a load circuit, and means comprising a switch manlyplacing both said tubes temporarily in parallel with each other withrespect to said source.

' ANDREW L. HOPPER.

